KaTeX: don't use autorenderer.

We no longer surround formulas with `\(..\)` or `\[..\]` and
rely on the autorenderer. Instead, we tell katex to convert
the contents of span elements with class "math". Since math has
already been identified, this avoids wasted time parsing
for LaTeX delimiters.

Note, however, that this may yield unexpected results
if you have span elements with class "math" that
don't contain LaTeX math.

Also, use latest version of KaTeX by default (0.9.0).

Closes #4946.

src/Text/Pandoc/Writers/HTML.hs

@@ -277,10 +277,10 @@ pandocToHtml opts (Pandoc meta blocks) = do
                       KaTeX url -> do
                          H.script !
                            A.src (toValue $ url ++ "katex.min.js") $ mempty
-                         H.script !
-                           A.src (toValue $ url ++ "contrib/auto-render.min.js") $ mempty
+                         nl opts
                          H.script
-                            "document.addEventListener(\"DOMContentLoaded\", function() {\n  renderMathInElement(document.body);\n});"
+                            "document.addEventListener(\"DOMContentLoaded\", function () {\n  var mathElements = document.getElementsByClassName(\"math\");\n  for (var i = 0; i < mathElements.length; i++) {\n    var texText = mathElements[i].firstChild;\n    if (mathElements[i].tagName == \"SPAN\") { katex.render(texText.data, mathElements[i], { displayMode: mathElements[i].classList.contains(\"display\"), throwOnError: false } );\n  }}});"
+                         nl opts
                          H.link ! A.rel "stylesheet" !
                            A.href (toValue $ url ++ "katex.min.css")
 
@@ -1065,8 +1065,8 @@ inlineToHtml opts inline = do
                 DisplayMath -> "\\[" ++ str ++ "\\]"
            KaTeX _ -> return $ H.span ! A.class_ mathClass $ toHtml $
               case t of
-                InlineMath  -> "\\(" ++ str ++ "\\)"
-                DisplayMath -> "\\[" ++ str ++ "\\]"
+                InlineMath  -> str
+                DisplayMath -> str
            PlainMath -> do
               x <- lift (texMathToInlines t str) >>= inlineListToHtml opts
               let m = H.span ! A.class_ mathClass $ x

src/Text/Pandoc/Writers/Math.hs

@@ -55,4 +55,4 @@ defaultMathJaxURL :: String
 defaultMathJaxURL = "https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.2/"
 
 defaultKaTeXURL :: String
-defaultKaTeXURL = "https://cdnjs.cloudflare.com/ajax/libs/KaTeX/0.8.3/"
+defaultKaTeXURL = "https://cdnjs.cloudflare.com/ajax/libs/KaTeX/0.9.0/"